By MICHAEL CIEPLY

May 8, 2013

But now the film producer may have to adopt the air of mystery for which Salinger was so famous. His company is preparing to offer a peek at a documentary about Salinger that is one of the unlikeliest projects ever to join its menagerie of potential Oscar contenders and box-office bait.

Selling the film may test even Mr. Weinstein’s Barnum-like skills. Moviegoers will be kept intentionally in the dark about what new information Mr. Salerno might have about the reclusive writer’s life — Mr. Salinger’s son, Matthew, challenges the notion that anyone close to his father in recent decades cooperated — and the Weinstein Company will have to strike a delicate balance in its marketing. It will have to raise the curtains a little, but not too much, as it seeks to build anticipation for the release.

As Mr. Salerno delivers his final cut, the marketers face particularly tough decisions about how much to show in a trailer. They must also figure out whether a screening at a late summer film festival, where prize contenders often start their march toward the Oscars, can work for a picture that has to protect its secrets while selling them.

It’s a difficult task in an era when fluttering fingers on smartphones can give away all the surprises. “I don’t know how we do this and not rob the audience,” Mr. Weinstein said in a telephone interview.

Associates of Mr. Salerno hint at never-before-seen photographs and interviews with aging intimates of Salinger, as well as secrets that they decline to describe. But there is skepticism. Speaking by phone, Matthew Salinger said that neither he nor his father were involved with the film. Nor, as far as he knows, were the seven or eight members of a small circle of people who were close to J. D. Salinger, he said. “There were barely enough people to form a circle in the last 30 or 40 years,” he said.

Asked whether he was confident that his father had not cooperated with Mr. Salerno, Mr. Salinger laughed. “That would be a yes,” he said.

Still, Mr. Weinstein has a proven track record with documentaries, having brought more than a touch of spectacle to the marketing of “Fahrenheit 9/11,”“Bully,”“Sicko,” and “Madonna: Truth or Dare.”

Mr. Weinstein snapped up “Salinger” quickly after Mr. Salerno showed it to him at an unusual 7:30 a.m. screening on Feb. 24, the day of the Academy Awards, according to people familiar with the film, who spoke on the condition of anonymity because of confidentiality agreements. On his way to the ceremony he sealed a deal for the film that is part of a three-prong strategy, including an “American Masters” TV segment on PBS in January and an oral history in book form that Simon & Schuster is to publish in September in tandem with the film’s theatrical release.

J. D. Salinger in 1952.

Antony Di Gesu / San Diego Historical Society, via Getty Images

Potential foreign buyers may get at least a glimpse of the film as early as this month during the Cannes Film Festival.

The sell for “Salinger” begins with a tantalizing question: What has Mr. Salerno got that lured the only three prospective buyers who watched a rough version to jump in? People involved with the project offer teasing suggestions of new revelations, but no details.

Buddy Squires a seasoned documentarian who collaborated with Mr. Salerno as a producer and a cinematographer on “Salinger,” said recently in a brief phone conversation that “it is safe to say no one has ever seen a film like this.” He declined to say more.

Jonathan Karp, Simon & Schuster’s president and publisher, said in an interview that the 750-page manuscript for the book “was revelatory, far beyond anything that’s been written about Salinger to date.” But like Mr. Squires, he would not reveal anything specific.

Susan Lacy, executive producer of the “American Masters” series, was just as circumspect. She said she was legally barred from discussing details of the film. But when asked whether it divulged any secrets, she replied, “Yes, I would just say that, yes, there are revelations.”

For the moment Mr. Salerno, who is finishing a final version, declines to be interviewed.

While he has not seen the film, Mr. Salinger expressed doubt that Mr. Salerno could meet the lofty expectations generated for the documentary. “I would only wish this were as serious-minded a piece of work as he would have us believe,” he said.

In a statement, the Weinstein Company said: “With due respect to Matt Salinger, he has not seen the film. We’ve seen the film, and unfortunately Matt Salinger does not have accurate information. Shane Salerno had unprecedented access and audiences will be able to see for themselves on Sept. 6.”

By the time Salinger died in January 2010 at 91, he was known as much for his retreat from the outside world as for a small but revered oeuvre that included “The Catcher in the Rye,” published in 1951, a short story collection and two other books that emerged over the next decade.

Although a former lover, Joyce Maynard, and his daughter, Margaret, both wrote widely discussed memoirs, enough mystery remained about his life, including the possibility of unpublished manuscripts, to leave an opening for Mr. Salerno. Around 2004 he began investigating Salinger as the subject of a self-financed film.

Reluctant to spoil any surprises: the movie producer Harvey Weinstein.

Jason Merritt / Getty Images for Aacta

The project offered Mr. Salerno, now 40, the chance to reinvent himself and transcend his Hollywood reputation as a writer of noisy action-oriented fare and of more sophisticated scripts that were never produced. He eventually spent more than $2 million of his own money, according to people familiar with the project.

He began knocking on doors around Mr. Salinger. Many slammed shut. But Mr. Salerno populated one version of his film with celebrity interviewees like Judd Apatow, Danny DeVito and John Cusack. Some who were interviewed seem to have forgotten being filmed long ago.

“It’s quite possible I was in a documentary, but I have no recollection of it,” said Robert Towne, the writer-director, when asked about an Internet Movie Database listing that credits him with an appearance.

John Guare, the playwright, said, “Now, I remember the guy, yes, but it was filmed so long ago.” He added that he vaguely recalled having spoken about a reference to Salinger in his play “Six Degrees of Separation.”

According to Mr. Salerno’s associates, the floodgates opened after Mr. Salinger’s death, when people close to the author began to offer recollections, photographs, and — if the promotional whisper is to be believed — more than a few details that had not previously been disclosed.

Roughly 200 were interviewed, according to the associates, and some signed confidentiality agreements. Neither Ms. Lacy nor Mr. Weinstein was shown all of the film’s confidential scenes before a deal was brokered. Even the film crew was ordered out of the room during some interviews. And in selling the movie, Mr. Salerno retained the cherished right of final cut.

Mr. Weinstein indicated that the secrets will be part of the fun as he and his company forge a strategy for selling “Salinger” to the masses. The challenge, he noted, is similar to that posed by “The Crying Game,” a Miramax hit that peddled its surprise ending with a “Don’t tell your friends” strategy two decades ago — before social media had demystified almost everything.

For now the plan is to hit the festival circuit, but with only part of the film, holding back the end until it opens in theaters, Mr. Weinstein said.

And if the movie is shown at Cannes, he was asked, will potential foreign buyers be allowed to see that part?

“No way!” he said.

Correction: May 11, 2013

An article on Thursday about the documentary film “Salinger,” scheduled for release in September, referred incorrectly to books published by J. D. Salinger after “The Catcher in the Rye.” One was a collection of short stories, not two. (Two other books each contained two long stories.)